The helicopter search noticed an avalanche at the peak the Americans were climbing.
An aerial search for two American mountaineers missing in Pakistan was suspended today, an official said, after an initial flight showed no sign of the men but indicated an avalanche on the peak they were climbing.
The climbers, Kyle Dempster and Scott Adamson, were attempting to summit the 6,960-metre Ogre-II peak in the Karakoram mountain range but did not return when expected.
Bad weather prevented an aerial search until Saturday, but the two helicopters that flew up to 7,200 metres found no sign of the men nor any camps, said Karrar Haidri, a spokesman for the Alpine Club
"It seems that a big avalanche had occurred, as they were going very well till August 23, but then it snowed a lot for four, five days," Haidri said today.
"The (helicopter) search was suspended on Sunday, as the family didn't request for a second-day search," he said, but added that the rescue mission is still formally under way and other mountaineers are searching via ground.
"The search for the two American climbers can only be called off by their family."
US media said both men are accomplished climbers, and Dempster had won the prestigious Piolet d'Or alpine climbing award twice.
Pakistan is popular with mountaineers as it rivals Nepal for the number of peaks over 7,000 metres. It also boasts K2, the world's second highest mountain.
During the summer, scores of climbers from all over the world attempt to scale various mountains in its northern region of Gilgit-Baltistan, near the Chinese border.
Dempster and Adamson began their ascent of the north face of Ogre-II peak on August 21. When they did not return as planned 10 days later, the Alpine Club raised the alarm.
© Thomson Reuters 2016